1. Field of the Invention
The present invention relates to a functional form capable of controlling the elution of functional components (such as catechins and saponins) even after water washing and of keeping its functionalities (such as antimicrobial properties or deodorizing properties) over a long period of time, and to a process for the production of the same.
2. Description of the Prior Art
As the infiltration of hygienic properties, caring for health attention to environmental improvement, it has become popular to impart antibacterial properties to articles in our immediate life. As bactericides for imparting antibacterial properties, inorganic bactericides containing a silver component and various organic (synthetic or naturally occurring) bactericides are known. However, an attention is being paid to the use of a catechin that is safe, has an antibacterial action and has a deodorizing action, as a bactericide.
In "Popular Science, Science of Teas, First Edition, published on Jun. 10, 1992, pp. 184-185 & pp. 210-211, by Shoka Shobo", it is described that components originated from teas, such as tea catechin, have good antibacterial properties, antiviral properties and deodorizing properties. Also, in "Great Health Power of Green Tea Catechin, First Printing, by Futami Shobo", it is described on different pages that the green tea catechin has superior antibacterial action (including fungicidal action), antiviral action and deodorizing action.
It is also known to use articles having a bactericide compounded therewith (i.e., those having a bactericide internally added thereto or incorporated therein) as a filter of air conditioners or air cleaners. For instance, Japanese Patent Laid-Open No. 99656/1989 mentions an antibacterial electret filter comprising polypropylene fibers having 0.1% or more of a bactericide incorporated therein. However, the bactericide that is used in the examples of this patent publication is thiabendazole as a synthetic bactericide.
Further, Japanese Patent Laid-Open No. 148407/1995 describes an antiviral filter comprising a filter material incorporated with a virus-inactivating agent comprising, as active ingredients, tea-extraction components. The tea-extraction components as referred to herein mean tea polyphenols, more specifically, epigallocatechin gallate, epicatechin gallate, epigallocatechin, epicatechin, etc. Further, an example of the filter material is polypropylene. In the examples of this patent publication, the polypropylene is mixed with 0.1% or more of the tea-extraction components, and the mixture is melt to form a film at from 200.degree. C. to 250.degree. C., which is then cut, fabricated into a non-woven fabric and formed into a filter.
However, in many cases, the antibacterial or deodorizing components originated from catechins are originally soluble in water or compatible with water. Accordingly, there is a problem that when a filter made from filaments having such an antibacterial or deodorizing component incorporated therein is washed with water, the antibacterial or deodorizing component elutes out, thereby impairing its effect.
That is, according to experiments made by the present inventors, it was found that, for example, in case where filaments obtained by incorporating a catechin in polypropylene, followed by melt forming, are used as a filter for air conditioners or air cleaners, although the filter exhibits good antimicrobial properties or deodorizing properties in the beginning, since the catechin is a water-soluble hydrophilic group-containing compound (in addition, the polypropylene is a polymer having no polarity), when the stained filter is dipped in water or washed with a synthetic detergent-containing water, a considerable amount of the incorporated catechin elutes out, thereby greatly lowering the antibacterial properties or deodorizing properties. Since the filter must be periodically washed, it is a great disadvantage that the active ingredient elutes out by the water washing.
In addition, when the antibacterial or deodorizing component is volatile at a certain temperature or higher, it is unavoidable that in a stage that such a component is incorporated in a resin material, followed by melt forming, a considerable amount of the relatively expensive antibacterial or deodorizing component volatilizes, resulting in loss in the quantity. Thus, when the amount of the antibacterial or deodorizing component to be compounded is increased, while expecting loss in the quantity due to the volatilization, not only the melt forming properties are lowered, but the resulting melt form is liable to be lowered in strength or surface roughening is caused.
Under such backgrounds, this invention is to provide a functional form ("Form" means molding article.), in which a functional component is hardly lost due to volatilization at melt forming, and the incorporated functional component such as a catechin is made water-resistant for fixing, so that the functional component does not readily elute out even after water washing, whereby functionalities such as antimicrobial properties or deodorizing properties can be kept over an extended period of time, as well as to provide a process for the production of the same.